Britain’s response to the rise of Islamic State may look like a mess of ambivalence, hesitation and all-round cluelessness – for which the prime minister’s antics with that surfboard probably stand as some kind of grim metaphor. But at the core of our politicians’ reaction to events in Syria and Iraq and the recruitment of British-born fighters, there are the remains of a familiar script: the one written by Tony Blair 13 years ago, when the events of 11 September 2001 began the disastrous phase of geopolitical history in which the then prime minister believed his moment had arrived.

Strange, perhaps, that when the awful consequences are now so obvious, the basics of his approach should linger on. First, there is the idea that British military intervention will ideally be part of what happens in the coming months – which David Cameron must know will be a difficult political sell, though his recent claim that the UK’s “military prowess” will be part of any solution surely indicates where his heart lies. Second, note the PM’s rhetoric: his claims that Britain itself is under threat and faces a “generational struggle” which “we will be fighting for the rest of my political lifetime” are Blair redux, once again echoing the jihadists’ own vanities. Third, on the domestic front, policy looks to have been polluted by classical Blairite doublethink, whereby our adversaries are said to represent the antithesis of democracy and the rule of law, but if they are to be defeated, the fundamentals of our liberty – “British values”, you could call them – will have to be set aside.

On the last score, people are again getting busy – despite warnings from such figures as Dominic Grieve, the former attorney general and Richard Barrett, MI6’s former global counter-terrorism director. Theresa May is set on adopting proposals put forward late last year by the government’s extremism task force, itself a somewhat panicked response to the murder of Lee Rigby: “banning orders for extremist groups”, “new civil powers to target extremists who seek to radicalise others”, and a duty on public bodies to involve themselves in anti-radicalisation measures. By way of betraying an attempt to get round existing statutes, the Daily Mail says the proposals will “focus on people who do not meet the threshold of breaking the law”, which has a distinctly Kafka-esque ring; what any of this might mean in practice remains unclear.

Other senior Conservative figures are sounding off too. With his eyes clearly on the Conservative leadership, Boris Johnson’s fondness for riding any populist wave in sight is reaching a new peak: someone who aspires to be prime minister now proposes that the most basic tenet of the law should be turned on its head, so that any Briton travelling without the state’s permission to Iraq or Syria should be presumed guilty of terrorism, unless they can somehow prove themselves innocent – a “swift and minor change”, he reckons, which even he must know is piffle.

He also suggests the return of the Blair government’s failed control orders – almost identical to the terrorism prevention and investigation measures (aka Tpims) that replaced them, though why let that get in the way of cheap rhetoric? Back in 2005, Johnson reckoned putting terrorism suspects under house arrest represented “deeply un-British” thinking that was “profoundly ignorant of the history of this country and the rights of its people”. Now, it seems, habeas corpus isn’t so important.

Alex Carlile, the former independent reviewer of terrorism legislation, thinks the same. So does the shadow home secretary, Yvette Cooper, averting her eyes not just from the supposedly dangerous subjects of control orders who simply absconded, but the fact that even Carlile’s successor, David Anderson, could cite only one subject of an order who had later been charged with a terrorist offence – which not only predated their house arrest, but did not result in a conviction. When politics is reducible to the desperate imperative to do something – anything – this is what happens: facts pale next to soundbites, with no end of pernicious consequences.

In much the same spirit, that supposed custodian of the libertarian flame David Davis ignores existing laws – in the Terrorism Acts of 2000 and 2006, and the Anti-Terrorism, Crime and Security Act of 2001, for what it’s worth – that could be used to prosecute returning Islamic State recruits, and instead advocates rendering British-born people who fight abroad stateless, a ploy at odds with some of our most basic treaty obligations and something usually associated with the governments of such thriving democracies as Myanmar and Zimbabwe. There are also murmurings about reviving the so-called snoopers’ charter, with its powers suggestive of Iran and China. At this rate, someone will soon propose ID cards.

These are precarious times not just for our basic liberties, but the language and concepts via which we understand them. Words such as “extremist” and “radicalisation” are hurled around as if they were exclusively bound up with the menace of Islamism; changes to the law are suggested as if they will address that particular problem, and then conveniently fade into the background.

But as the modern experience of terrorism legislation proves – not least section 44 of the Terrorism Act 2000, familiar to protesters against everything from the international arms trade to the expansion of Heathrow – today’s urgent measure can easily become tomorrow’s blanket provision, to be used against anyone who might get in the authorities’ way. With the subtlest of political shifts, whom might the definition of “extremist” eventually include? Trotskyists? Anarchists? Even the more frazzled fringes of Ukip?

No one should doubt that the challenges of how to force the retreat of Islamic State and minimise its attraction to young British men are fantastically urgent and complicated ones. But equally, if western societies are to present any coherent alternative to the horrific ideology currently defining headlines about the Middle East, they will have to display a lot more confidence in their own essential principles. “Civil rights, democracy, pluralism and the rule of law are the source of progress and a key component of lasting security,” Cameron said in 2007, which mightn’t be a bad start. We might also think again about a simple question, first heard back when Blair was in his pomp and we were being pushed down such a disastrous road: how is it that people can harp on about threats to the British way of life, while frantically chipping away at its very foundations?